Structure de la phase quadratique de PbTeO3
Cristallisation dans le systeme quadratique, groupe P4 1 et affinement jusqu'a R=0,048. La structure est constituee d'anions TeO 3 2− legerement deformes relies par des cations Pb 2+
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Persistent photocurrent in amorphous chalcogenides
The long-term photocurrent decays following the steady-state photoexcitation have been reported in amorphous ${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$, ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$, GeSe, ${\mathrm{GeSe}}_{2}$, and ${\mathrm{GeS}}_{2}$ films. The photocurrent decays empirically as exp(-${\mathrm{Ct}}^{\ensuremat…
Empirical tight-binding calculation of dispersion in the linear optical properties of tetrahedral solids
The empirical linear combination of atomic orbitals approach toward calculating band structures is extended to include third-nearest neighbors, and used to calculate both the conduction and valence bands of a wide range of semiconducting materials. Using these bands, we calculate the dispersion of the dielectric const…
Study of monolayer polymerization using nonlinear optics
Optical second harmonic generation has been used to study the polymerization of a monolayer of vinyl stearate or octadecyl methacrylate spread at the air/water interface. Rapid polymerization occurred when monolayers were irradiated with ultraviolet light, while some slower polymerization occurred when certain redox i…
Structure of High-Density Amorphous Ice by Neutron Diffraction
The static structure factor and pair distribution function of high-density amorphous ${\mathrm{D}}_{2}$O ice, which is made by apparently melting ice I at 10.5 kbar and 77 K, have been determined by neutron diffraction at 17 K and zero pressure. The pair distribution function, scaled to 10 kbar, is compared with the s…
Galvanic corrosion of copper alloys in contact with a highly alloyed stainless steel in seawater
Galvanic pairs of varying area ratios have been exposed to seawater on the Swedish west coast for one year. In most couples the cathodic member has been the highly alloyed stainless steel 254 SMO and the anodic member one of several copper alloys. Muntz metal was rapidly attacked by dezincification at all area ratios,…
Spin Dynamics in a Quasi-Two Dimensional Antiferromagnet MnTiO3
The spin dynamics in a quasi-two dimensional antiferromagnet MnTiO 3 has been studied in the temperature range between 7 K and 300 K by means of inelastic neutron scattering with the multi-analyser crystal spectrometer (MAX). The exchange interaction parameters were determined from the spin-wave dispersion relations a…
Defect-induced hyper-Raman spectra in cubic zirconia
Hyper-Raman scattering of cubic zirconia and ${\mathrm{CaF}}_{2}$ is measured at room temperature. For a ${\mathrm{CaF}}_{2}$ crystal, the frequencies of the TO and LO modes with ${T}_{1u}$ symmetry are determined to be 260 and 480 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$, which are in good accord with the results o…
Wall-Induced Orientational Order of a Liquid Crystal in the Isotropic Phase—an Evanescent-Wave-Ellipsometry Study
Using an evanescent-wave ellipsometric technique, we have studied the wall-induced orientational order in the isotropic phase of ${4}^{\ensuremath{'}}\ensuremath{-}n\ensuremath{-}\mathrm{pentyl}\ensuremath{-}4\ensuremath{-}\mathrm{cyanobiphenyl}$ (5CB) at a silane-treated glass surface. Near the isotropic-nematic tran…
Volume expansion of diamond during ion implantation
A study was made of the volume expansion obtained during ion implantation of 170-keV fluorine ions into diamond under ambient temperature. By concluding that the expansion is not related to the onset of amorphization or graphitization of the ion-damaged layer, a simple theoretical description of the phenomenon could b…
Low-temperature properties of crystalline (KBr)1−x(KCN)x: A model glass
The thermal properties of (KBr${)}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$(KCN${)}_{\mathrm{x}}$ single crystals have been studied between 0.05 and 100 K over the entire compositional range. For 0.25\ensuremath{\le}x\ensuremath{\le}0.70, these crystals have the thermal conductivity that is typical for all structurally d…
Preferential site occupation and magnetic structure of Nd2(CoxFe1−x)14B systems
Rietveld analyses of room-temperature neutron diffraction data for seven Nd2(CoxFe1−x)14B alloys (x=0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) are reported. Throughout the entire composition range the Nd2Fe14B-type tetragonal crystal structure is maintained, with the lattice constants decreasing significantly as the Co concentrat…
Stability of Dendritic Crystals
We present an integrodifferential-operator formulation of the problem of linear stability around the selected needle crystal pattern in dendritic crystal growth. We show by explicit computation that (a) all members of the discrete set of allowed steady states aside from the fastest are unstable and (b) the fastest suc…
Spectroscopy of the O-H and O-D stretching vibrations inSrTiO3under applied electric field and uniaxial stress
High-resolution measurements of the ir stretching bands of OH and OD at about 3500 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ and 2600 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ in monodomain ${\mathrm{SrTiO}}_{3}$ crystals yield spectroscopic data for a local anharmonic-oscillator model. The optical polarization depe…
Light scattering by adsorbates at Ag particles: Quantum-mechanical approach for energy transfer induced interfacial optical processes involving surface plasmons, multipoles, and electron-hole pairs
A quantum-mechanical approach for surface-enhanced optical processes is given, which may solve an old controversy regarding the surface enhancement mechanisms: The present formalism contains three terms: The first is equivalent to the classically derived electromagnetic enhancement; the second represents a loss term d…
Electronic structure of amorphous III-V and II-VI compound semiconductors and their defects
The local electronic structure of bulk and defect sites has been calculated for nine amorphous III-V compound semiconductors and for two amorphous II-VI compound semiconductors using the tight-binding recursion method. We find that structural disorder in a chemically ordered, tetrahedrally coordinated network causes a…
Magnetic Properties of Layered Compound MnPS3
Magnetic properties of a layered compound MnPS 3 were investigated by means of magnetic susceptibility, high field magnetization and electron spin resonance. Temperature and angular dependence of EPR line width are characteristic of 2D-antiferromagnet. The main exchange interaction in the a b -plane is estimated to be…
Zero-reflectivity high spatial-frequency rectangular-groove dielectric surface-relief gratings
Using rigorous coupled-wave analysis, high spatial-frequency rectangular-groove surface-relief phase gratings are shown to be capable of exhibiting zero reflectivity. Thus these corrugated surfaces may act as antireflection coatings in a variety of applications. The diffraction characteristics of rectangular-groove su…
Study of ferroelectric properties of deuterated tris-sarcosine calcium chloride
By means of permittivity, spontaneous polarisation and polarisation reversal measurements the authors studied the influence of the substitution of deuterium atoms for hydrogen on the ferroelectric properties of tris-sarcosine calcium chloride (TSCC). Although most of the protons in the hydrogen bonds were substituted…
The role of impurities on the deviation from Paschen's law of SF6
Deviations to Paschen's law for SF 6 at high pressures are commonly explained by field enhancement due to protrusions supposed to exist at the surface of the electrodes. New experiments for positive polarity allow the authors to draw a different conclusion, i.e. to ascribe these deviations to the impurities of the gas…